Biology 20... very confusing... i'm doing an online course and have no teacher to refer to so please help...?

Question

Identify the factors that might lead to regular population cycles of the red-backed voles. Explain how each factor can limit the population of this mammal. (Total 4 marks; 2 - biotic; 2 - abiotic)

Answer 1

Biotic factors influencing population cycles usually results from predator-prey relationships:

1.  The red-backed vole's prey's population grows when the population of red-backed voles is low.  As a result, the voles have more food, more survive to produce offspring, and the population surges.  As the population grows, the prey's population decreases, less food is available, less voles survive to reproduce and their population decreases.

2.  The same as the first one, only the voles are the prey to another predator.

As for abiotic factors, one that comes to mind is seasonal changes.  Maybe it's the case that many voles die in the winter months, so the population cycles annually.  Unfortunately, I can't think of a second abiotic factor, but maybe someone else will have an idea.

Hope this helps.